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General Information, Facts & Tables
[Bolt Tightening Torques]

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Overview

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The tables below list the recommended tightening torques for various categories of threaded steel bolts.
 

British Association

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Nominal
Thread Dia

Quality

A

P

R

S

T

X

8 BA

1.9

2.8

4.4

4.9

5.6

8.1

7 BA

2.7

4.0

6.2

6.9

8.0

11.5

6 BA

3.9

5.6

8.7

10.0

11.3

16.1

5 BA

5.9

8.6

13.4

14.9

17.3

24.8

4 BA

8.4

12.3

19.0

21.3

24.6

35.3

3 BA

12.5

18.3

28.2

31.6

36.6

52.4

2 BA

19.1

28.0

43.3

48.4

56.0

80.2

1 BA

27.4

40.2

62.1

69.4

80.0

115.0

0 BA

40.2

59.0

91.1

101.9

118.0

169.0

Torque values given in pounds force per foot (lbt ft)
 

Imperial

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Nominal Thread Dia

A Quality

P Quality

R Quality

Thread

BSW

BSF

UNC

UNF

BSW

BSF

UNC

UNF

BSW

BSG

UNC

UNF

1/4"

3.6

4

3.6

4

5.3

5.9

5.3

6

8.2

9.1

8.2

9.3

5/16"

7.4

7.9

7.4

8.2

11

12

11

12

17

18

17

19

3/8"

13

14

13

15

19

21

19

22

30

32

30

34

7/16"

21

23

21

23

31

33

31

34

48

51

48

53

1/2"

31

34

32

36

46

50

47

53

70

77

73

82

9/16"

46

50

46

52

68

73

68

76

104

113

105

117

5/8"

64

68

64

72

93

100

94

106

144

154

145

164

3/4"

113

118

114

126

166

173

167

185

256

268

256

286

7/8"

181

191

183

201

266

280

269

295

411

433

415

456

1"

272

288

274

299

400

422

402

438

617

652

621

678

1 1/8"

387

411

389

434

567

602

570

637

876

931

881

984


Nominal Thread Dia

S Quality

T Quality

W Quality

Thread

BSW

BSF

UNC

UNF

BSW

BSF

UNC

UNF

BSW

BSF

UNC

UNF

1/4"

9.1

9.1

10

10

11

12

11

12

15

17

15

17

5/15"

19

19

20

21

22

23

22

24

31

33

31

34

3/8"

33

33

36

38

38

41

39

44

55

59

55

63

7/16"

53

53

58

60

62

67

62

69

88

95

89

99

1/2"

79

82

86

91

91

100

94

106

130

143

135

152

9/16"

117

117

126

131

135

146

137

152

194

210

195

217

5/8"

161

162

172

183

187

200

188

212

267

286

269

304

3/4"

286

288

300

319

331

347

333

370

474

497

477

529

7/8"

460

464

484

510

532

560

537

590

762

802

769

845

1"

690

695

729

757

799

844

804

877

1 144

1 208

1 152

1 255

1 1/8"

979

985

1 041

1 100

1 134

1 205

1 140

1 273

1 624

1 725

1 632

1 823

 

Torque values given in pounds force per foot (lbf ft).
 

Metric

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Nominal Thread
Dia (mm)

4.6 Quality

4.8 Quality

5.6 Quality

5.8 Quality

6.6 Quality

Coarse

Fine

Coarse

Fine

Coarse

Fine

Coarse

Fine

Coarse

Fine

1.5

0.08

-

0.1

-

0.1

-

0.13

-

0.11

-

2

0.16

-

0.21

-

0.19

-

0.26

-

0.26

-

2.5

0.32

-

0.43

-

0.4

-

0.53

-

0.48

-

3

0.57

-

0.76

-

0.71

-

0.95

-

0.85

-

4

1.3

-

1.8

-

1.7

-

2.2

-

2

-

5

2.7

-

3.6

-

3.3

-

4.5

-

4

-

6

4.5

-

6.1

-

5.7

-

7.6

-

6.8

-

7

7.6

-

10.2

-

9.5

-

12.7

-

11.4

-

8

11

11.8

14.7

15.7

13.8

14.8

18.4

19.7

16.5

17.7

10

21.8

23

29.1

30.7

27.3

28.8

36.4

38.4

32.8

34.6

12

38.1

41.6

50.8

55.5

47.6

52

64

69

57

62

14

60.6

66

81

88

76

82

101

110

91

99

16

95

101

126

134

118

126

158

168

142

151

18

130

146

174

195

163

183

217

244

195

220

20

185

205

246

273

231

256

308

342

277

307

22

251

276

335

368

314

345

419

460

377

414

24

319

347

425

463

399

434

532

579

479

521

27

467

504

622

672

583

630

778

841

700

757


Nominal Thread
Dia (mm)

8.8 Quality

9.8 Quality

10.9 Quality

12.9 Quality

14.9 Quality

Coarse

Fine

Coarse

Fine

Coarse

Fine

Coarse

Fine

Coarse

Fine

1.5

0.2

-

0.23

-

0.29

-

0.34

-

0.4

-

2

0.42

-

0.47

-

0.58

-

0.7

-

0.82

-

2.5

0.85

-

0.96

-

1.2

-

1.44

-

1.7

-

3

1.5

-

1.7

-

2.1

-

2.6

-

3

-

4

3.5

-

4

-

5

-

6

-

7

-

5

7.1

-

8

-

10

-

12

-

14

-

6

12.1

-

13.6

-

17

-

20.4

-

23.8

-

7

20.3

-

22.8

-

28.6

-

34.3

-

40

-

8

29.4

31.5

33.1

35.4

41.3

44.3

49.6

53.2

57.9

62

10

58.3

61

66

69

82

86

98

104

115

121

12

102

111

114

125

143

156

171

187

200

219

14

162

176

182

198

227

247

273

297

318

346

16

252

268

284

302

355

377

426

453

497

528

18

347

391

391

439

488

495

586

659

683

769

20

492

546

554

615

693

768

830

922

969

1 076

22

670

736

753

828

941

1 035

1 130

1 241

1 318

1 448

24

851

926

957

1041

1 196

1 301

1 436

1 562

1 685

1 822

27

1 245

1 344

1 401

1513

1 750

1 891

2 100

2 269

2 450

2 648

Torque values given in newton metres (Nm).
 

Unified Fine

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Nominal
Thread Dia

Quality (Ibf in)

A

P'

R

S

T

X

No. 2

1.8

2.7

4.1

4.6

5.3

7.6

No. 3

2.8

4.1

6.3

7.0

8.1

11.6

No. 4

3.9

5.7

8.9

9.9

11.5

16.4

No. 5

5.5

8.1

12.5

14.0

16.2

23.1

No. 6

7.5

11.0

17.0

19.0

22.0

31.5

No. 8

12.9

18.9

29.2

32.6

37.8

54.0

No. 10

20.3

29.8

46.1

51.5

59.6

85.4

No. 12

29.9

43.8

67.7

75.6

87.5

125.0

Torque values given in pounds force per foot (lbf ft).